Interceptor guidance systems are currently of great interest, in particular when engaging accelerating targets. In general, prior-art guidance systems require that the target acceleration be estimated. If the target acceleration is incorrectly estimated, it is possible for the interceptor to be commanded to very high accelerations near the intercept point, and the target may be missed altogether if the interceptor commanded acceleration is greater than its capability.
U.S. Pat. No. 6,244,536, issued Jun. 12, 2001 in the name of Cloutier describes an air-to-air homing missile guidance algorithm based on a state-dependent Riccati equation solution of a spherical-based nonlinear intercept representation of the intercept kinematics problem. The algorithm also provides characteristics asymptotically stabilizing the intercept kinematics achieved with the classic proportional navigation or PRONAV intercept algorithm but provides reduced hunting instability and other fuel-consuming and time consuming missile maneuvers. The algorithm is in the form of four state equations, two equations for an angular acceleration embodiment and two for a linear acceleration embodiment. Each such embodiment includes seven state variables each having a gain coefficient of complex fraction form; each embodiment is additionally refined for differing cross-channel couplings. Each algorithm avoids need to estimate the time-to-go parameter and achieves indirect rather than faulted direct minimization of missile miss distance when provided with accurate target and missile acceleration data.
US Statutory Invention Registration H1980, issued Aug. 7, 2001 in the name of Cloutier describes an interceptor guidance system for intercepting accelerating targets in which it is assumed that the interceptor is slowing.
U.S. Pat. No. 6,845,938 issued Jan. 25, 2005 in the name of Muravez describes an interceptor guidance system in which small-angle approximations result in periodic inaccuracies which may result in guidance law destabilizations. The approximations are periodically corrected.
Improved and or alternative interceptor guidance control systems are desired.